Identification of time-varying fuzzy systems

This paper discusses the identification of time-varying fuzzy systems. A square-root type recursive algorithm with variable forgetting factor is presented to estimate the parameters of systems. Numerical examples are provided to illustrate the performance of the identification algorithm. An interesting discovery of this paper is that, for a linear system, a fuzzy model may have a frequency response close to that of a conventional model, say, a difference equation model, although the orders of two models may be different.